Bryce Harper had one of the greatest 19-year-old seasons in baseball history. / H. Darr Beiser USAT

by Paul White, USA TODAY Sports

by Paul White, USA TODAY Sports

Mike Trout could count on his American League Rookie of the Year award Monday. There was more suspense for Bryce Harper in the National League.

But the results of the voting by the Baseball Writers Association of America provide another opportunity to digest an unprecedented historic performance combo by players so young.

Trout turned 21 on Aug. 7 -- in the midst of a season matched only by a trio of Hall of Famers. The Angels' often spectacular defender in center field hit .326 with a .923 OPS, led the AL with 129 runs and 49 stolen bases.

Harper was a teenager until four days after his Washington Nationals were eliminated from the NL playoffs. Still, he hit .270 with 22 homers and an .817 OPS.

Trout's victory had been a foregone conclusion for months, any discussion pushed aside to make room for the more spirited debate about his AL Most Valuable Player credentials. We'll learn the results of that battle with Detroit's Miguel Cabrera on Thursday.

The only players younger than Trout with a higher OPS were Mel Ott, Ted Williams and Al Kaline -- all with plaques in Cooperstown.

Another eight names show up on the list of highest OPS by someone Trout's age or younger -- Frank Robinson, Mickey Mantle, Vada Pinson, Orlando Cepeda, Tony Conigliaro, Jason Heyward, Ty Cobb and Ken Griffey Jr. -- before we get to Harper.

But Harper was 19 for the entire season.

The 14-month age difference between Trout and Harper might not seem so significant and will diminish further as time goes on.

But it's huge at this stage of their careers.

Harper's year is unprecedented for a player who was a teenager the entire season. The benchmark had been Ken Griffey Jr., who was a month younger than Harper in his debut 1989 season. Griffey hit .264 with 16 homers, 61 RBI and a.748 OPS before turning 20 that November.

What's most remarkable about Harper's season is how he finished. There's perhaps no bigger worry about a young player in the majors than how he'll hold up over the grind of a season longer than any he's experienced.

Harper has 145 more plate appearances this year than in his 2011 pro debut. Over those final 145 plate appearances this year -- the final 35 games of the season -- Harper hit .338 with a 1.080 OPS and had 10 of his 22 homers, 22 of his 59 RBI.

That's the stretch that probably won him the NL Rookie of the Year. Compare that finish with Arizona pitcher Wade Miley, the front-runner for much of the season.

Miley, nearly six years older than Harper, also had a career-high workload. In his final four starts, which comprised the 25 innings over his previous high, Miley had a 5.11 ERA. His ERA was 5.15 over his final seven starts, a sharp reversal from his 2.80 to that point.

Trout's finish was as solid as the rest of his season -- he hit .288 with a .902 OPS over his final 132 plate appearances, the difference over his previous pro high.

If there was anything for him to overcome, it was his start. After a nondescript 40-game taste of the majors in 2011 (he hit .220), Trout began 2012 in the minors. That lasted all of 20 games into a season surprisingly going sour for the Angels. A 6-14 start probably cost them a postseason berth -- just 10-10 over that stretch would have left them tied for a playoff spot.

The Trout impact wasn't immediate -- .182 over his first six games, though the Angels at least managed to go 3-3 -- but it was quite the jolt when it came.

In the next 69 games until Trout reached his high-point .357 batting average, he hit .371 with 15 homers, 40 RBI and was 30-for-33 in stolen base attempts. Moreover, the Angels were 42-27, a pace that wins any division in the majors this year.

But that's more the stuff of which MVP discussions are made.

The sheer numbers are what will drive Monday's Rookie of the Year announcements -- and none are more noteworthy than the ages of Trout and Harper.